msk0657 wrote:
stonecold wrote:
If a and b are two numbers such that a*b = 10; Is a an integer ?
A-) 2a is an integer
B-) b is a not an integer
Given that a and b are two numbers such that a*b = 10 and asking us to find the if a is integer ?
Stat 1: 2a = integer.
if a = 1 (integer) then 2a is 2 - integer.
if a = 1/2 (non-integer) then 2a is 1 - integer... we get different answers..
.Insufficient.Stat 2: b is not an integer
then out of ab = 10 , for ex : if b is 1/10 then a has to be 100 . Then in case b is rational then a has to be integer if at all if we want to get ab = 10.....
.Sufficient.
Hence option B is correct.
I am sure sure i get your solution..
What if the question had said 19 instead of 10?
then the test case approach would have been longer one
i think the logic may here be => "If the product of two integers is an integer then one of them must be an integer"
Hence B .
The question didn't about 19..ok if it is 19 ... then take a or b as 38 or a or b as 1/2...even then it works quickly... Then we have two cases for a itself i.e 38 or 1/2.
"If the product of two integers is an integer then one of them must be an integer" - You are correct...if it is in the question, if they ask about which one is integer then you have to try the test case approach itself...